1. Field of The Invention
The subject invention relates to resonant mode power supplies, e.g., for television receivers.
2. Description of The Related Art
Television receivers include power supplies for suppling power to the various circuit components. Generally, these power supplies are in the form of switched-mode power supplies in which a dc voltage is applied to one end of the primary winding of a flyback transformer. The other end of the primary winding is connected to ground through a switching element which is controlled to switch on and off at a determined frequency. The switched power to the transformer is then transferred to the secondary winding for providing the output power.
It has been found that resonant mode power supplies have higher efficiencies and are especially suited for power levels higher than 150W and for power supplies that need to be miniaturized, e.g., power supplies for battery charging. In a resonant mode power supply, an oscillating circuit, which is typically a series oscillating circuit, is supplied through a first switching element with a direct voltage by which the oscillating circuit is excited. After one-half of an oscillating period, the first switching element is opened, and the oscillating circuit is connected to ground through a second switching element, and as a result, the capacitor of the oscillating circuit discharges again, and the oscillation is thus continued. An oscillation can accordingly be excited by alternating opening and closing of the two switching elements.